Yeah. Fermented beverages like wine have all kinds of chemicals in, as they're only 12-16% alcohol usually. So they can react to themselves, and usually have a colony of yeast still living inside. Their flavor changes over time because it's still reacting and if you let it go too long it becomes vinegar.

The distilled stuff is boiled to vapor and thus is almost pure concentrated ethanol, then diluted back down with water. There's very little in un-aged booze and it's all uniform. No reactions take place in the bottle. Placing in a cask, on the other hand, lets you get all kinds of chemistry going on, but slowly. So 20 year old whiskey is indeed radically different from 2 year old whiskey. But 18 and 20 might not change that much, even if the price does.